The best way for you is the Indian Navy 10+2 B.Tech Entry Scheme of Indian Navy. This is the best way to pursue a career in engineering and serve the nation at the same time. The candidates qualifying get a chance to pursue a four-year degree course under the 10+2 (B.Tech) Cadet Entry Scheme. The shortlisting criteria of candidates are JEE Main All India Rank. Hence appearing for JEE Main is mandatory for the candidates. After that they call for SSB interview which is normally held five to six times in the year. After being selected, the candidates get to pursue B.Tech in Indian Naval Academy, Ezhimala, Kerala. After those four years, they get permanent posting in the Indian Navy.
This is the link to a past advertisement of the same, but it will pretty much give you the idea: https://www.joinindiannavy.gov.in/files/event_attachments/10701-11-0015-1718,10+2,%20B.Tech(Eng).pdf